Kelling J S, DiMarco A F, Gottfried S B, Altose M D
J Appl Physiol (1985). 1985 Dec;59(6):1752-6. doi: 10.1152/jappl.1985.59.6.1752.
This study compared the respiratory responses to ventilatory loading in 8 normal subjects and 11 quadriplegic patients with low cervical spinal cord transection. Progressive hypercapnia was produced by rebreathing. Rebreathing trials were carried out with no added load and with inspiratory resistive loads of 5 and 16 cmH2O. l-1 X s. Measurements were made of ventilation and of diaphragmatic electromyographic activity. Base-line hypercapnic ventilatory responses were significantly lower than normal in the quadriplegic patients, but the effects of resistive loading on the ventilatory responses were comparable in the two groups. The change in peak moving-average diaphragmatic electrical activity (DI peak) for a given change in CO2 partial pressure (PCO2) and DI peak at PCO2 55 Torr increased significantly with resistive loading both in the normal subjects and the quadriplegic patients. In the normal subjects, but not in the quadriplegic patients, inspiratory duration increased progressively with increasing resistance. The increase in DI peak during ventilatory loading in the normal subjects was a consequence of inspiratory prolongation. In contrast, in the quadriplegic patients during breathing against the larger resistive load, there was a significant increase in the average rate of rise (DI peak divided by the time from onset to peak) of diaphragmatic activity. The change in DI rate of rise for a given change in PCO2 increased to 137 +/- 13% (SE), and the DI rate of rise at PCO2 55 Torr increased to 128 +/- 8% (SE) of control values. These results indicate that compensatory increases in diaphragmatic activation during ventilatory loading occur in quadriplegic patients in whom afferent feedback from rib cage receptors is disrupted.
本研究比较了8名正常受试者和11名颈髓低位横断的四肢瘫痪患者对通气负荷的呼吸反应。通过重复呼吸产生渐进性高碳酸血症。在无附加负荷以及吸气阻力负荷分别为5和16 cmH₂O·l⁻¹·s的情况下进行重复呼吸试验。测量了通气量和膈肌肌电活动。四肢瘫痪患者的基线高碳酸血症通气反应显著低于正常水平，但两组中阻力负荷对通气反应的影响相当。在正常受试者和四肢瘫痪患者中，随着阻力负荷增加，给定二氧化碳分压（PCO₂）变化时的膈肌电活动峰值移动平均值变化（DI峰值）以及PCO₂为55 Torr时的DI峰值均显著增加。在正常受试者中，吸气持续时间随阻力增加而逐渐延长，但在四肢瘫痪患者中并非如此。正常受试者通气负荷期间DI峰值的增加是吸气延长的结果。相反，在四肢瘫痪患者中，在对抗较大阻力负荷呼吸时，膈肌活动的平均上升速率（DI峰值除以从起始到峰值的时间）显著增加。给定PCO₂变化时DI上升速率的变化增加至对照值的137±13%（标准误），PCO₂为55 Torr时的DI上升速率增加至对照值的128±8%（标准误）。这些结果表明，在胸廓感受器传入反馈中断的四肢瘫痪患者中，通气负荷期间膈肌激活的代偿性增加会发生。
